Pump piston packing



March 2 1943. R. M. MAGNUSON 2,312,430

PUMP PISTON PACKING Filed Oct. 9, 1941 me-N702:

HTTQQ/Vfy Qm MM/mwumv Patented Mar. 2, 1943 EUMP PISTON PACKING Roy M. Magnuson, Campbell, Calif., assignor to Food Machinery Corporation, San Jose, Calif., a corporation of Delaware Application October 9, 1941, Serial No. 414,331

Claims.

This invention relates to pumps and particularly pumps of the ram type in which the piston itself extends through a stufiing box.

Pumps of this general type are employed where high liquid pressures are required and it is necessary to maintain the stuffing box relatively tight in order to prevent leakage. It is possible, however, to tighten this box to such an extent as to cause damage to the piston and it is ditficult to prevent this happening where these pumps must be operated without expert supervision.

It is accordingly an object of my invention to provide a pump of the type mentioned in which adequate pressure may be maintained on the packing about the piston while at the same time preventing the accidental application of suflicient pressure to this packing to damage the piston.

It is a further object of my invention to provide a pump of the type mentioned in which means is provided for giving a signal to a person adjusting the pressure on the packing when that pressure reaches a pre-determined value.

The manner of accomplishing the foregoing objects, as well as further objects and advantages will be made manifest in the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a diagrammatic cross sectional view of a pump illustrating a preferred embodiment of my invention.

Fig. 2 is a fragmentary view of a portion of the structure shown in Fig. 1 and illustrating the operation of the signal giving means of the invention.

Fig. 3 is an enlarged perspective view of the principal operating elements in the signal giving means of the invention.

Referring specifically to the drawing, these show a pump it which includes a crank case H providing a cross head slideway l2 and having secured thereto a cylinder supporting frame I3, the latter having an opening l4 concentric with the slideway l2. Fitting into the opening l4 and secured to the frame [3, is a cylinder assembly 26 which includes a cylinder 2!, a valve head 22 and a cylinder head 23.

Slidable in the slideway I2 is a cross head 24 carrying a ram type piston 25 which extends into an opening 26 formed in the lower end of the cylinder 21. The cylinder assembly 26 has a pump chamber 36 which is substantially larger than the diameter of the piston 25, the right hand or lower end of the chamber 36 disposed outside the piston 25 being closed by an annular wall 3| provided on the cylinder 2 I.

Disposed in the chamber 36 about the piston 25 is a stufiing box 32 in which a quantity of packing 46 is compressed between the wall of the cylinder and the piston 25 by a gland or packing follower 4|. The left hand or upper end of the follower 4| has an end wall 43 provided with a screw centering depression 44. The follower 4| also has suitable openings 45 through which liquid may circulate in the pumping operations of the pump l6. 7

The valve head 22 is provided with suitable intake and exhaust valves 56 and 5| which are constructed in a manner well known in the art and are provided for the purpose of facilitating the pumping of liquid by the pump l6 when the piston 25 is reciprocated in the pump chamber 36.

The cylinder head 23 has a subordinate bore 52, a shoulder 53 between this bore and the pump chamber 36 and an end wall 54 through which extends a screw hole 55 about which is formed a bonnet stuiling box 56. Extending inwardly through this hole and stufiing box is a screw 51, the inner end of which is adapted to rest in the screw centering depression 44 in the packing follower 4|.

The cylinder head 23 also has a guide spider 66, this spider including a ring 6| which rests against and is secured to the shoulder 53, and a hub 62 which has a screw guiding hole 63 and is connected to the ring 6| by webs 64. The hub 62 has an annular serrated upper face providing teeth 65 which radiate outwardly from the center of the hole 63. Screwed onto the screw 5'! and disposed in the bore 52 of the head 23 is a nut 16 having a radially serrated face providing teeth H which are adapted to mesh with the teeth 65 of the spider 66. Portion 12 of the nut 16 is turned down so as to extend into a helical expansion spring I3 coiled thereabout and also disposed in the bore 52.

Operation In the normal operation of the pump l6 the piston 25 reciprocates in the packing 46 thus causing liquid to be sucked through the valve 56 into the pump chamber 36 and expelled from the latter through the valve 5 I. The liquid pressure heads against which the pump I6 operates are usually very high so that it is necessary to maintain considerable pressure on the packing 46 in order to prevent liquid leaking outwardly between this packingand the piston 25. My invention provides a means whereby this may be accomplished without the danger of inadvertent- 'of teeth against each other.

ly applying so much pressure to the packing 40 as to damage the piston 25.

This means is embraced in the follower 4| and in the mechanism provided on the head 23. The spring 13 is selected so that the pressure required to compress this spring from the position in which this is shown in Fig. 1 to the position in which it, is shown; Fig. 2 is that maximum pressure which can safely be applied to the packing 40 by the follower 4|. Thus whenever it is desired to tighten up the packing 40 the operator applies a wrench to the head of the screw 51 and rotates this screw. It being assumed that at this time the follower 4| is' not applying the maximum pressure aforesaid against the packing- 40, the spring 13 will be forcing the nut 10 toward the spider hub 62 so that the teeth 'II of this nut will mesh with the teeth 65 of this hub, as shown in Fig. 1. The meshing of these teeth prevents the rotation of the nut 10 relative to the hub 62 so that the rotation of the screw 51 causes this to be screwed through the nut wand shift the follower 4| toward the .wall. 3|, thereby compressing the packing 40.

When the pressure thus applied by the follower 4| to the packing 4:) equals the maximum which it is desired to be appplied to the packing, the nut 13 starts compressing the spring '53 thereby withdrawing the teeth H from meshingrelation with the teeth .65. Thus freed, the nut H3 rotates with the screw 51 when the latter is further rotated, thus making it impossible for-the operator to place any higher pressure aginst the packing 4i) than that just necessary to; compress the spring 13 enough to disengage the nut 70 and permit this to rotate with the screw.

The disengagement of the teeth II from the teeth 65 and the rotation of the nut I are naturally accompanied by a clashing of the two sets This produces a metallic sound which is an audible signal to the operator that hehas applied the maximum amount of pressure possible to the packing 40 so that he may discontinuerotating the screw 51.

It is also to be noted that after thus havingoperated the pressureapplying mechanism of my invention the pressure of the spring 13 against the packing 4i}. is maintained until the latter-has worn down to such an extent that the spring is ableto force the nut Ill-toward the spider hub 62 sufficiently to reseat the nut snugly against the hub 62 with the teeth II and (SE-snugly meshing with each other.

What-I claim is 2. 1

1. In a pump the combination of means forming a chamber having a piston opening; means forming a, stuffing box about said opening; 'a piston extending through said stufiing 'box;

2. In a pump the combination of: means forming a. pump chamber having a piston opening; means forming a stufling box about said opening; a piston extending through said stuffing box; means for applying pressure to the packing in said stufling box to cause the packing to more tightly conform to said piston; and means rendering said pressure applying means inoperative to apply increased pressure to said packing when the pressure applied to said packing has reached a given value.

3. In a pump the combination of: means forming a pump chamber having a piston opening; means forming a stufiing box about said opening; a piston extending through said stuffing box; means for applying pressure to the packing in said stufiing box to cause the packing to more tightly conform to said piston; means rendering said pressure applying means inoperative to apply-increased pressure to said packing whenthe pressure applied to said packing has reached a given value; andmeans for giving a signal to the operator when the pressure applied to said packing has reached said value.

4. In a pump the combination of: a pump cylinder having a piston opening and a cylinder head opposite said opening; a piston extending through said opening; means forming a stuffing box about said piston and including packing and a follower to apply pressure to said packing; a pressure screw provided in said head and positioned to apply pressure to said follower and to be operated from the exterior of said head; a nut on said screw; spring means between said nut and said head for applying pressure to said nut and through said nut and saidscrew to said follower when said-screw is screwed through said nut; and means for. reventing the. rotation of said nut with said screw until said spring pressure has reached a. pre-determined value and then releasing said nut for rotation with said screw. 7

5. In a pump the combination of: a pump cylinder having a piston opening and a cylinder head opposite said opening; a piston extending through said opening; means forming a stuffing box about said pistonand, including packing. and a follower to apply pressureto said packing; a pressure screw provided in said head and positioned to apply pressure to said follower and to be operated from the exterior of said head; .a nut on said screw; spring means betweensaid nut and said head for applying pressure to said.

, nut and through said nut and said screw to said means forapplyingpressure to the packing in said stuihng box to cause the'packing to more tightly conform to said piston; and means giving an audible signal to the operator when said pressure has reached a pre-determined value.

follower when said screw is screwed through said.

ROY M. MAGNUSON. 

